The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
This invention relates to methods for treating subterranean formations using proppants and other solid materials, and in particular, methods and systems for fracturing subterranean formations penetrated by a wellbore using fluids with rheology properties which help achieve layered particle structures to form highly conductive fluid paths in the fracture.
Hydrocarbon producing subterranean formations penetrated by wellbores are often treated by fracturing the subterranean formation and depositing proppant particle packs or other solids in the fractures. In fracturing operations, solid particles are suspended in water or a viscous fluid at the surface and carried to a fracture in the wellbore in which they are to be placed at a designed concentration and pump rate. After the proppant is placed, the carrier fluid is returned to the surface via the washpipe, or some of the fluid is leaked off into the formation during the treatment. The propped fracture produced functions to keep the fracture open.
Two common problems often experienced as a result of fracturing subterranean formations are difficulties in the clean-up of the fracturing fluid and low retained conductivity. In the first case, the clean-up of the fracturing fluid can be partially inhibited as the placed particles have the tendency to retain fluid components, such as viscosifiers. In the later case, the pathways for production of formation fluids can be blocked by trapped fluid components and/or a substantially homogeneous distributed proppant layer filling the fracture.
There have been attempts in the art to place particles heterogeneously in hydraulic fracturing to create higher fracture conductivity than uniform particle placement. Currently, there is no established method to reliably achieve a productive heterogeneous placement, i.e., a placement that reliably succeeds in creating more productive fracture treatments by ensuring clear paths along substantially the total length of the fracture.
The need exists in fracturing operations for reliable heterogeneous particle placement methods and systems which provide improved clean-up and retained conductivity after treatment.